MSPP 개요 (1) < EOS 기술 > 코위버㈜

1. EOS EoS (Ethernet over SDH) - GFP (Generic Framing Procedure) : Ethernet 신호를 SDH 전송로를 통하여 전송하기 위한 Framing 방법 - Vcat (Virtual Concatenation) : 사용자의 Bandwith에 맞게 SDH에서 사용되는 기본적인 단위 신호(VC12/VC3/VC4)를 n배 하여 SDH Frame에 할당하는 방법 - LCAS (Link Capacity Adjustment Scheme) : 서비스의 중단 없이 가상연결그룹의(VCG)의 Channel을 Add/Remove 하는 기능 SDH ㄴSDH MUX/DEMUX Native Interfaces ? VC Virtual Concatenation LCAS Link Capacity Adjustment Scheme GFP Generic Frame Procedure Ethernet Ficon Escon Fiber Channel Edge Core Adaptation Customer Operator 2 / 21

Regenerator Section Layer Multiplexer Section Layer 2. EOS 계층구조 Physical Layer Regenerator Section Layer Multiplexer Section Layer VC-4 Path Layer TU Path Layer VC-3 Path Layer SDH Layer Model VCAT Layer Encapsulation Layer Payload Added Layers EOS 기술 추가 (GFP, VCAT, LCAS) 3 / 21

3. EOS 매핑 STM-1 GFP (frame mapped) Ethernet Frame 4 / 21 GFP Payload Core Header Payload FCS (optional) GFP Payload P O H H4 C2 Pointers STM-1 GFP (frame mapped) Ethernet Frame 1 4 9 10 Ethernet frame 4-64 64-1522 270 GFP LAPS 2 7 6 42-1500 Preamble SFD Destination address Source MAC Client length / type Data / PAD Length/ = 802.1Q Tag Type Control Info. 4 / 21

4. GFP GFP (Generic Frame Procedure) - GFP-F (Framed Mapped) : 하나의 Client Frame을 하나의 GFP Frame에 Mapping (1:1 매핑) : Minimum Overhead (e.g. Etherent ) : Variable Length : 4 ~ 65539 bytes - GFP-T (Transparent Mapped) : Client Characters를 Fixed GFP Frame에 직접 Mapping (Block 단위 매핑) : Minimum Latency (e.g. Fiber Channel) 5 / 21

GFP Client Specific Aspect Ethernet IP/PPP POS RPR FC FICON ESCON Other Client Signals GFP Common Aspect (Client Independent) GFP Client Specific Aspect (Client Dependent) Framed Mapped GFP Transparent Mapped SONET/SDH Path OTN Path 6 / 21

6. GFP 프레임 구조(1) GFP Client Frame Structure GFP Frame PLI (15:8) 16-Bit Payload Length Indicator cHEC Field (CRC-16) Payload Headers (4-64 Bytes) CLIENT PAYLOAD INFORMATION FIELD GFP Frame Optional Payload FCS (CRC-32) 1 2 3 4 5 6 7 8 Core Header Payload Area # of OCTETs 4 4 -65535 PLI (15:8) PLI (7:0) cHEC (15:8) cHEC (7:0) Notes: PLI Codes of 0-3 reserved for GFP control frames cHEC Polynomial = x16 + x12 + x5 + 1 cHEC calculated over Core header only. Core header scrambled with B6AB31E0H 7 / 21

Continued 6. GFP 프레임 구조(2) GFP Client Frame Structure GFP Frame Payload Headers (4-64 Bytes) CLIENT PAYLOAD INFORMATION FIELD GFP Frame Optional Payload FCS (CRC-32) 1 2 3 4 5 6 7 8 TYPE tHEC Extension Header Field eHEC Notes: 2-byte Payload Type field PTI - Payload Type Identifier(3 bits) PFI - Payload FCS Indicator (1 bit) EXI - Extension Header Identifier (4 bits) UPI - User Payload Identifier (8 bits) PTI UPI PFI EXI Continued 8 / 21

6. GFP 프레임 구조(3) GFP Client Frame Structure PTI UPI EXI Notes: 2-byte Payload Type field PTI - Payload Type Identifier(3 bits) PFI - Payload FCS Indicator (1 bit) EXI - Extension Header Identifier (4 bits) UPI - User Payload Identifier (8 bits) PTI UPI PFI EXI 9 / 21

Start of Frame Delimiter Destination Address (DA) 7. 이더넷 신호 Encapsulation GFP Ethernet Encapsulation Specified per ITU-T G.7041/Y.1303 Start of Frame Delimiter Destination Address (DA) Source Address (SA) Length/Type MAC Client Data FCS # of OCTETs 7 1 6 2 46-1500 4 1 2 3 4 5 6 7 8 PAD Preamble PLI Field cHEC Field Type Field tHEC Field GFP Payload Information Field 0 - 60 IEEE 802.3 Ethernet MAC Frame GFP Frame Extension Header Optional FCS 10 / 21

8. VCAT VC-4-2v VCAT (Virtual Concatenation) - Fine Granularity(VC12/VC3/VC4) 단위로 n배 하여 BoD(Bandwidth of Demand) 서비스 제공 가능. - 각 VC단의 H4(High order) / K4(Low order)를 이용하여 VC의 SQ (Sequence Indicator)와 FC(Frame Counter)를 부여하여 같은 VCG 내의 VC들을 구별 하며 Sorting . - 각 VC들이 다른 경로를 통하여 수신 가능하기 때문에 도착시간이 모두 다르게 되므로 지연시간(Differential Delay)을 보상하기 위하여 Buffer를 이용. VC-4-2v VC-4 #2 #1 Path 2 Path 1 Differential Delay 11 / 21

Gigabit Ethernet (1G) VC-4-16c 42% VC-4-7v  85% 9. VCAT 효율성 Vcat (Virtual Concatenation) Rate Efficient Granularity X Capacity In steps of VC12-Xv 1~46 2,176kbps to 100,096kbps 2,176 kbps VC3-Xv 1~21 48,384kbps to 1,016,064 kbps 48,384kbps VC4-Xv 1~7 149,384 kbps to 1045688 149,384kbps Data Rates 기존 방식(CCAT) VCAT Ethernet (10M) VC3 20% VC-12-5v  92% Fast Ethernet (100M) VC-4 67% VC-12-46v  100% Gigabit Ethernet (1G) VC-4-16c 42% VC-4-7v  85% 12 / 21

10. VCAT 장점 VCAT (Virtual Concatenation) 장점. 1. Use existing SONET/SDH network Contiguous Concatenation 구성 시 모든 Network의 장치는 반드시 Contiguous Concatenation 구성 VCAT 구성 시 Edge Node에서만 VCAT 구성 2. Choose the most suitable size of Container SDH Bandwidth을 효율적으로 사용하기 위해 가입자 신호 형태에 따라 Container 상자 선택 가능.(VC12/VC3/VC4) 3. 연접된 VC 채널들을 다른 라인(경로)를 통해 전송가능. 1Gbps 서비스를 위해 최소 가용 밴드 폭이 VC4 x 7개 이상이 필요했지만, 다른 경로의 가용 Bandwidth을 이용하여 전송가능 하므로 효율적인 망 구성이 가능. 13 / 21

11. VCAT 구성 C-4-Xc 페이로드 크기 =X*149.760Mbit/s ( 260*9*8000*8) VC-4-Xv X X+1 X*260 125s 페이로드 크기 =X*149.760Mbit/s ( 260*9*8000*8) VC-4-Xv를 구성하기 위해 X개의 독립된 VC-4로 매핑 J1 B3 C2 G1 F2 H4 F3 K3 N1 Virtual concatenation sequence와multi-frame indicator로 사용됨 261 VC-4#1 VC-4#X VC-4-Xv 각각의 VC-4는 자신의 path overhead를 갖는다. 1 X+1 Fixed stuff 14 / 21

1st multiframe indicator MFI1 (bit 1-4) 12. VCAT 순서 표시 H4 byte 1st multi-frame number 2nd multi-frame number Bit1 Bit2 Bit3 Bit4 Bit5 Bit6 Bit7 Bit8 1st multiframe indicator MFI1 (bit 1-4) Sequence indicator MSB (bit 1-4) 1 14 n-1 Sequence indicator LSB (bits 5-8) 15 2nd multiframe indicator MFI2 MSB (bit 1-4) n 2nd multiframe indicator MFI2 LSB (bits 5-8) CTRL 2 GID 3 Reserved (“0000”) 0(1) 4(5) CRC-8 6(7) Member status MST 8(9) RS_Ack 10 1(1,1) 0(1,1) 1(0,0) 1(0, 1) 11,12,13 Sequence indicator SQ MSB (bit 1-4) Sequence indicator SQ LSB (bits 5-8) n+1 15 / 21

13. LCAS LCAS (Link Capacity Adjustment Scheme) LCAS는 Vcat의 Source 와 Sink사이의 사용자의 Bandwidth을 서비스 중단 없이 증감 할 수 있는 기능을 제공. VC-4 #1 VC-4 #2 VCG VCG VC-4 #1 Path 1 VC-4 #3 VC-4 #1 VC-4 #2 VC-4 #2 VC-4 #3 VC-4 #3 LOS VC-4 #4 VC-4 #4 Path 2 VC Member의 Los 발생시 전체 VC Member을 Drop (LCAS=Disable) , LCAS Enable시 Sink단에서 해당 VC Member status을 Fail로 보고 Source 단에서 Ctrl 비트를 이용하여 DNU Message을 Sink단에 전달 하고 Sink Node에서는 해당 VC을 Demapping 하지 않으므로 계속적인 서비스제공 가능 Drop 16 / 21

14. LCAS 장점 LCAS 정의 Virtual Concatenated Group(VC-n-Xv)를 이용하여 Virtual Container 개수를 동적으로(Dynamically) 변화(증감) 시키는 기능. LCAS 장점 Flexibility in Bandwidth Allocation In Service 상태에서 서비스에 영향 없이 Ethernet 신호에 대한 대역폭을 증가/감소할 수 있음. More Efficient Protection Extra Traffic 활용을 통한 정상 상태에서 최대 Throughput 제공. 장애로 인한 절체 시 Topology 변경 없음으로 , 재연결을 위한 IP Routing Protocol 불필요. 17 / 21

Source to Sink Communication Sink to Source Communication 15. LCAS 특징 LCAS 단 방향 프로토콜 - Forward 와 Inward 방향은 독립적인 운용 - 한쪽 링크의 VCG의 변화는 다른 링크에 어떤 영향을 미치지 않음 - LCAS는 항상 Backward 방향으로 적어도 하나의 VC을 이용하여 Ack 정보를 수신 받을 수 있음을 가정한다. Multi-frame Indicator Frame counter Same VCG member 동일 Group Identification Synchronize Source & Sink Sequence number Unique number Control bit CRC check CRC GID CTRL SQ MFI Source Source to Sink Communication Sink Sink to Source Communication MST RS-Ack Member Status Re-Sequence Acknowledge 18 / 21

16. LCAS 제어신호 1 2 87 J1 H4 Bits 1-4 H4 Bits 5-8 (MFI1) Member status (MST) MSBs 8 Member status (MST) LSBs 9 RS-Ack (“000x”) 10 Reserved(“0000”) 11 12 13 Sequence indicated SQ MSBs 14 Sequence indicated SQ LSBs 15 MFI2 MSBs (Bits 1-4) MFI2 LSBs (Bits 5-8) 1 CTRL 2 GID(“000x”) 3 4 5 CRC-8 6 7 B3 C2 G1 F2 H4 Z3 Z4 N1 Path Overhead STS-1 Payload Capacity Two stage Multiframe allows differential delays up to 256ms 1st Multiframe Indicated (MFI1) is incremented every 125us frame - Stage 1 multiframe cycle =16 x 125us = 2ms 2nd Multiframe Indicated(MFI2) is incremented every multiframe - Stage 2 multiframe cycle =256 x 2ms = 512ms High order control packet (used for virtual Concatenation and LCAS) spans from MFI1 = 8 to MFI1 =7 in next multiframe LCAS High Order Control Packet Info 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 MFI1 MFI2 Sequence Ind (SQ) CTRL GID Member Status (MST) RS-Ack 35 36 37 38 39 40 41 42 OK FAIL Multiframe indicated allows compensation for differential delays Identifies a member of a VCG Fixed ADD NORM EOS IDLE DNU Pseudo-Random bit sequence-identical for all member of a VCG Toggled when all members of VCG validated 19 / 21

17. LCAS 동작 The mechanism for Link Capacity Adjustment Scheme allows communication between the transmit/source and receive/sink functions so that both ends are in synchronism through control packets which are embedded in the H4 byte. The information exchanged, in addition to Multi-Frame Indicator (MFI) field and Sequence Indicator (SQ) field from the Source to the sink for framing purposes Multi-frame Frame 번호 H4 Bits Control (CTRL) field N+1 2 1-4 Group Identification (GID) 3 4 Bits 1-3 set to“0” CRC 6&7 From Source to Sink Multi-frame Frame H4 Bits Member Status (MST) field N 8&9 1-4 Re-Sequence Acknowledge (RS-Ack) bit 10 4 Bits 1-3 set to“0” From Sink to Source 20 / 21

18. LCAS 제어신호 의미 Member status 000 Rs-ACK 0000 Sequence # Bits 1-4 Sequence# Bits 5-8 MFI-2 Bits 1-4 MFI-2 Bits 5-8 Control 000 GID CRC LCAS functions by transmitting the future state of each member during the current multi-frame 2 through the control field To identify membership of a virtual group, the same pseudo –random pattern of 215 –1 is transmitted by each member via the Group Id number ( GID bit). A CRC-8 field protects the contents of the control packet which are rejected if the CRC check fails , given that LCAS is used. Control Field value (Bits 1-4) Command Remarks 0000 FIXED Default for non-LCAS mode .This is an indication that this end uses fixed bandwidth 0001 ADD This member is about to be added to the group Do not use the payload 0010 NORM Normal transmission i.e. an active member 0011 EOS End of Sequence indication i.e. the active member with the highest active sequence number and Normal transmission 0101 IDLE This member is not part of the group or about to be removed. Do not use payload 1111 DNU Do Not Use (the payload) the Sk side reported FAIL status 21 / 21